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Currently, the existing similar simulation is still limited in the following aspects: un-rotatable laboratory devices, the difficulty in the pavement on steep seams and great error of the experimental data.

To address above-mentioned problems, this study combined theoretical analysis and numerical simulation and developed a rotatable experimental system for similar simulation on steep coal seam mining on the premise of ensuring experimental safety.

The present experimental system mainly consists of the model support, the rotation system and the bearing system. By taking into account the experimental requirements and actual laboratory space, the sizes of the model support and the bearing system were determined. Considering the requirements in space limit and rotation stability, the rotation mode of vertical sliding on the left side and the horizontal sliding on the lower side was designed.

Using programmable logic controller automatic angle control technology, the rotation angle, velocity and displacement of the model can be automatically adjusted and controlled so as to achieve safe rotation and precise control. Finally, the calculation method of the mass of the required similar materials for paving the coal strata at different inclination angles and in different horizons was analyzed, and the related mass proportion calculation software was developed.

In 1968, Garrett Hardin identified a class of common goods that suffer under traditional market mechanisms. As a result, institutions become pivotal in defining acceptable consumption behavior. This paper describes the results of an agent-based computer simulation used to study how institutional forces shape consumption patterns. The results suggest common-interested behaviors support a greater population at a higher quality of living; however, exclusively common-interested behaviors result in underutilized commons, and the whole is generally less well off. Overall, when populations generally act in the common-interest, the commons, the population and individuals all experience higher quality outcomes than when they act in generally or exclusively self-interested ways. The paper frames further applications in terms of managing growth for long-term sustainability.

The purpose of this paper is to compare real fabric drape images and virtual fabric drape images created by a commercial software. To achieve an in-depth comparison, actual and virtual drape shape properties were considered under three categories: drape area, number of nodes and shape of folds. The results of this research are expected to be useful to improve the reality and accuracy of fabric and garment.

Five different fabrics were selected for this study. Fabrics’ mechanical properties were tested by fabric assurance for simple testing method, while drape properties were measured by a Cusick drape meter. A commercial garment simulation was used to generate virtual fabric drapes. Real fabric drape images and virtual fabric drape images were analyzed by an image analysis software and results were used to calculate drape properties. Regression analysis was performed to compare real fabric drape and virtual fabric drape properties.

Differences between real fabric drape and virtual fabric drape were stated clearly. Simulation software was found to be insufficient to reflect drape area. However, simulations were quite successful corresponding to the number of nodes. Only one simulation had +2 nodes than its actual counterpart. This study showed that area and node shape representations of simulation software should be improved while node numbers are sufficiently represented.

There are alternative 3D garment simulation software available to the fashion business. All these companies are working on to improve their simulation reality and accuracy. Some of them are also offering various equipment to measure the fabric properties. In this study, Optitex 3D Suite was selected as the simulation software due to several reasons as explained in this paper. However, other simulation programs might also be employed to perform virtual fabric drapes. Furthermore, in this study, the drape images of five woven fabrics were compared. The fabric selection was done according to a pre-test and consequently similar fabrics were determined to be the subject of the study. However, the more the number of the fabrics, the better the comparison and eventually the better the assessment of simulation success. Therefore, it is prospected to test more fabrics with versatile fabric properties for further studies.

Drape shape was observed from three perspectives: drape area, node numbers, and node shapes. Dealing the problem from these perspectives provided an in-depth comparison of real and virtual drapes. In this study, standard deviation of peak angles was used to explain node distribution that is new to the literature to the authors’ knowledge.

Gas insulated systems, such as gas insulated lines (GIL), use insulating gas, mostly sulfur hexalfluoride (SF₆), to enable a higher dielectric strength compared to e.g. air. However, under high voltage direct current conditions, charge accumulation and electric field stress may occur, which may lead to partial discharge or system failure. Therefore, numerical simulations are used to design the system and determine the electric field and charge distribution. Although the gas conduction shows a more complex current–voltage characteristic compared to solid insulation, the electric conductivity of the SF₆ gas is set as constant in most works. The purpose of this study is to investigate different approaches to address the conduction in the gas properly for numerical simulations.

In this work, two approaches are investigated to address the conduction in the insulating gas and are compared to each other. One method is an ion-drift-diffusion model, where the conduction in the gas is described by the ion motion in the SF₆ gas. However, this method is computationally expensive. Alternatively, a less complex approach is an electro-thermal model with the application of an electric conductivity model for the SF₆ gas. Measurements show that the electric conductivity in the SF₆ gas has a nonlinear dependency on temperature, electric field and gas pressure. From these measurements, an electric conductivity model was developed. Both methods are compared by simulation results, where different parameters and conditions are considered, to investigate the potential of the electric conductivity model as a computationally less expensive alternative.

The simulation results of both simulation approaches show similar results, proving the electric conductivity for the SF₆ gas as a valid alternative. Using the electro-thermal model approach with the application of the electric conductivity model enables a solution time up to six times faster compared to the ion-drift-diffusion model. The application of the model allows to examine the influence of different parameters such as temperature and gas pressure on the electric field distribution in the GIL, whereas the ion-drift-diffusion model enables to investigate the distribution of homo- and heteropolar charges in the insulation gas.

This work presents numerical simulation models for high voltage direct current GIL, where the conduction in the SF₆ gas is described more precisely compared to a definition of a constant electric conductivity value for the insulation gas. The electric conductivity model for the SF₆ gas allows for consideration of the current–voltage characteristics of the gas, is computationally less expensive compared to an ion-drift diffusion model and needs considerably less solution time.

The purpose of this paper is to find out the applicability of the many-body dissipative particle dynamics (MDPD) method for various real fluids by specifically focusing on the effects of the MDPD parameters on the MDPD fluid properties.

In this study, the MDPD method based on van der Waals (vdw) equation of state is employed. The simulations are conducted by using LAMMPS with some modifications of the original package to include the many-body features in the simulation. The simulations are investigated in a three-dimensional Cartesian box solution domain in which MDPD particles are distributed. In order to evaluate the MDPD liquid characteristics for a stationary liquid film, self-diffusivity, viscosity, Schmidt number (Sc) and surface tension, are estimated for different MDPD parameters. The parameters are carefully selected based on previous studies. A set of single-droplet simulations is also performed to analyze the droplet characteristics and its behavior on a solid-wall. Besides, the relationship between the characteristic length in the DPD simulations and scaling parameters for the stationary liquid-film case is discussed by employing the Ohnesorge number.

The results show that the liquid properties in the MDPD simulations can be widely ranged by varying the MDPD parameters. The values are highly influenced by the many-body feature in the conservative force which is not included in the original DPD method. It is also found that the wetting ability of the MDPD fluid on solid walls can be easily controlled by changing a many-body parameter. The characteristic length between the MDPD reduced unit and real unit is related for the stationary liquid-film case by employing the Ohnesorge number.

The present parametric study shows that the liquid properties in the MDPD method can vary by carefully controlling the MDPD parameters, which demonstrates the high-potential applicability of the method for various real fluids. This will contribute to research areas in multi-phase transport phenomena at nano and sub-micron scales in, for example, fuel cells, batteries and other engineering devices involving porous media.

Providers of cloud computing storage services (CCSS) charge offers in several unit bundles for a lump sum per bundle. This non-linear pricing approach is known as a bucket-pricing plan (BPP). If a customer exploits the purchased bucket, he/she can opt for the next higher bucket or refrain from further CCSS use. CCSS suppliers are faced with an optimization problem concerning the number of buckets as well as their lower and upper storage volume boundaries. The purpose of this paper is to develop a model, which supports CCSS suppliers in deriving a BPP-structure and which maximizes their profit in varying market constellations.

The authors develop a multi-period model of tariff choice decisions of private customers of CCSS. The model is applied in Monte Carlo simulations to determine profit-maximal tariff structures as a function of different market characteristics such as median demand saturation, demand heterogeneity, average price per storage unit and bucket ceiling allocation (identical size of each bucket within the frame set by the lower and upper overall boundary, varying sizes of the buckets offered, so that the interval between two ceilings consecutively increases for subsequent buckets) and type of a customer’s utility function.

The simulation analysis suggests that demand heterogeneity and average price per unit are the most influential factors for CCSS tariff structure optimization. Price plans with more than two buckets tend to generate higher profits than simple schemes with two buckets only if demand heterogeneity is low and the average price per storage unit is high and/or median saturation level of customers is low.

Despite the popularity of BPP among providers of CCSS for consumers, there is a lack of scholarly modeling work on the profit implications of the number of buckets entailed in a scheme and the size/ceilings of the various buckets on offer. The model suggested in this paper is a first step toward narrowing this research gap.

The aim of this paper was to explore the use of objective fabric parameters in 3D virtual garment simulation.

Two methods (fabric assurance by simple testing and Browzwear's fabric testing kit) of obtaining objective fabric measurements and the derived parameters for virtual garment simulation were studied. Three parameters (extension, shear and bend) were investigated to establish whether the selected virtual software derived comparable parameters from the objective fabric measurements.

It was found that the conversion from the objective fabric measurement data to the required parameters for virtual simulation varied significantly. Manual analysis of the objective measurements showed the two test methods to be comparable for extension and shear parameters; However, some adjustment to the test method was required. The third parameter to be investigated (bending rigidity) concluded that the test methods and results obtained from the two different apparatus were not comparable and recommended further experimentation using a different testing technique.

Future research should be conducted on a larger variety of fabrics ensuring comparable loads are used in the testing of the extensibility parameters. An expansion of this preliminary study should give more conclusive evidence of the trends observed.

Objective measurement of extension, shear and bend properties was investigated in relation to the derived parameters for a selected virtual simulation package. An understanding of such parameters will aid the general industry in adapting 3D virtual garment simulation as part of the standard product development process, resulting in a significantly shorter product development cycle.

We use simulations from a detailed dynamic computable general equilibrium (CGE) model to study three broad policies toward illegal workers in U.S. employment: supply restriction (tighter border security), demand restriction (prosecution of employers), and legalization through a guest-worker program with a visa tax. From the point of view of the welfare of legal residents, the results strongly favor the third option. In our welfare analysis, we use a six-part decomposition. This identifies effects on the occupational mix of legal employment as a major factor. Throughout the chapter, model results are explained through arguments and diagrams that will be familiar to economists, particularly those working in trade. No familiarity with the underlying CGE model is assumed. Technical details on our labor market assumptions are given in the Appendix.

The purpose of this paper is to investigate the development process of the fire whirl in the fixed-frame facility and focus on the impacts of the fire whirl’s vortex core on the formation and flame structure of the fire whirl.

The complex turbulent reacting flame surface is captured by the large eddy simulation turbulence closure coupled with two sub-grid scale (SGS) kinetic schemes (i.e. the chemistry equilibrium and steady diffusion flamelet). Numerical predictions are validated thoroughly against the measurements by Lei et al. (2015) with excellent agreements. A double maximum tangential velocity refinement approach is proposed to quantify the vortex cores’ instantaneous location and region, addressing the missing definition in other studies.

The numerical results show that the transition process of the fire whirl is dominated by the vortex core movement, which is related to the centripetal force. The unsteadiness of the fully developed fire whirl was found depending on the instantaneous fluctuation of heat release rate. The steady diffusion flamelet scheme is essential to capture the instantaneous fluctuation. Furthermore, the axial velocity inside the vortex core is the key to determining the state of fire whirl.

Due to intensive interactions between buoyant fires and ambient rotating flow, the on-set and formation of fire whirl still remain largely elusive. This paper focused on the transition process of fire whirl between different development stages. This paper provides insights into the transition process from the inclined flame to the fire whirls based on the centripetal force.

This paper presented and compared two SGS kinetic schemes to resolve the fire whirl development process and the unsteadiness of its vortical structures. The modelling framework addresses the shortcoming of previous numerical studies where RANS turbulence closure and simplified combustion kinetics was adopted. Numerical results also revealed the fire whirl transition process and its relationship to centripetal force.

Subtractive rapid prototyping (SRP) uses layer‐based removal from a plurality of orientations in order to create geometry in a highly automated manner. However, unlike additive means, the method can be inefficient due to redundant cutting operations on previously machined regions. The purpose of this paper is to present process planning methods for SRP, specifically dealing with stock material management in multiple setup operations.

Analysis of remaining stock material was performed by considering slices of respective stereolithography (STL) models. Further, an initial approximation was made of accessibility to enable iterative visibility analysis. The combination of these approaches led to efficient and fast algorithms. After analysis, the slices could be converted back to useful STL models through polyhedral reconstruction.

This method of approximation yields results similar to exact geometry. Using remaining stock data from this approach leads to a significant reduction in tool path length and processing time in SRP.

This paper presents novel methods of geometric representation and inaccessible volume calculation for four‐axis layer‐based machining and shows a successful implementation in an SRP system.